We thank Hammoudi et al . for their stimulating comments on our article “Diastolic Stress Echocardiography in the Young: A Study in Nonathletic and Endurance-Trained Healthy Subjects” and the related editorial.

In their letter, Hammoudi et al . mention that the E/e′ ratio should not be used as a noninvasive estimate of left ventricular (LV) filling pressures in normal subjects, because of the preload dependence of e′ found in hearts with preserved relaxation. It should be kept in mind, however, that the evidence leading to this caveat for using E/e′ in normal hearts was based on a small study performed in seven healthy subjects. In contrast, normal values for the assessment of diastolic function with Doppler echocardiography at rest have been defined in larger cohorts. On the basis of these well-established data, E/e′ values are supposed to be low (i.e., ≤8 on average in normal subjects up to 64 years of age). In line with this, we observed low resting E/e′ values (6.8 ± 1.3 for septal E/e′ and 5.0 ± 0.8 for lateral E/e′) in healthy subjects <40 years of age.

The E/e′ ratio has been shown to remain stable during exercise in a healthy, middle-aged population (mean age, 59 years). However, corresponding data have thus far not been published for a younger population. We therefore assessed diastolic function during exercise in young healthy subjects (<40 years of age) and looked for possible differences between endurance-trained and nonathletic subjects. In our study, E/e′ during exercise showed a slight increase compared with rest but remained within the normal range. This was true for endurance-trained as well as for nonathletic young subjects. As discussed in the editorial, our normal E/e′ data with exercise confirmed the corresponding previous findings in older healthy individuals.

We agree with Hammoudi et al . that the data on correlation of E/e′ with invasively measured LV filling pressure during exercise are conflicting. Whereas some groups have described good correlations with invasive LV end-diastolic pressures for patients with normal and abnormal Doppler echocardiographic responses to exercise, others could not confirm these findings. It must be kept in mind that these studies included only relatively small numbers of patients. Additional studies will be needed to further elucidate the link between Doppler echocardiography and invasive hemodynamic measurements during exertion. We agree with Hammoudi et al . that to date, the indication for diastolic stress echocardiography to assess exertional LV filling pressures should be made on a patient-to-patient basis.

In our study, we did not perform invasive assessment of LV filling pressures. Therefore, we are not able to comment on the actual pressure values during exertion in the investigated population without being speculative. Nevertheless, our work may help define the normal diastolic stress echocardiographic response in the young. Given the well-accepted age dependence of Doppler echocardiographic assessment of diastolic function at rest, we believe that this is useful information.